[TS] Parse a string to an integer-优快云博客

本文介绍了一种将字符串转换为整数的方法，并提供了一个JavaScript函数实现。该函数使用ASCII码进行转换，支持正负数输入。此外，还包含了一个简单的测试用例验证功能正确性。

A common interview question is to write  a function that converts  a  string into an integer e.g. "123" => 123.  This  function  is commonly  called  atoi because  we  are  converting  an  ASCII  string  into  an  integer.

In this lesson we cover the proper way to do this in JavaScript which is parseInt along with implementing it using basic ascii math.

Writing a function whichi convert string to number, to do that

1. Convert each "string" char to ASCII code by using

str.charCodeAt(index)

2. Each round, we should increase the acc value by *10

function atoi (str: string): number {
  const zeroCode = '0'.charCodeAt(0);
  console.log("zeroCode", zeroCode);
  
  let sub = 1;
  if(str[0] === '-') {
    sub = -1;
    str = str.substring(1);
    console.log("sub string", str);
  }
  
  return sub * str.split('')
    .reduce((acc, curr) => {
    acc = acc * 10 + (curr.charCodeAt(0) - zeroCode)    
    return acc;
     }, 0)
}

console.log(atoi("123")); //123
console.log(atoi("-123")); //-123

import { atoi } from './atoi';

test('basic', () => {
  expect(atoi('123')).toBe(123);
  expect(atoi('-1123')).toBe(-1123);
});

转载于:https://www.cnblogs.com/Answer1215/p/7623896.html